Mechanism for opening furnace-stack dampers by the closing of the furnace door



NOV- 9 J.. J. A. MILLER MECHANISM FOR OPENING FURNAQE STACK DAMPERS BY THE CLOSING OF THE FURNACE DOOR Original Filed Dec. 7, 1922 2 Sheets-Sheet 1 Nov. 9 1926. 1,606,375

J A. MILLER J. MECHANISM FOR OPENING FURNACE STACK DAMPERS BY THE CLOSING OF THE FURNACE DOOR Original Filed 8 '7, 1922 2 Sheets-Sheet 2 v I Q wdlmlz f/ Fatentetl Nov. 9, 19.26.

UNITED STATES PATENT orr ca.

JOHN J. A. MILLEEI, OF DENVER, COLORADO.

MECHANISM FOR OPENING FURNACE-STACK DAMPERS BY THE GLOSTNG OF THE FURNACE DOOR.

Application filed. December 7, 1922, Serial No. 605,489. Renewed. March 31, 1926.

7 My invention relates to improvements in mechanism for opening furnace stack dampers, by closing of the fire door of'said furnace, and a cooperating gravity device for closing said damper.

The object of the present invention is to provide mechanism which is connected with the stack damper of a furnace, and which is adapted to be actuated by the fire door of the furnace when the said door is closed, thereby to open said stack damper; a cooperating gravity device acting to close said damper within a predetermined period after the closing of the said fire door.

Further, to provide a smoke stack damper with mechanism adapted to be actuated by the furnace fire door when said door is closed, thereby to open said damper, and oil controlled gravity means connected with said mechanism for closing said damper within a predetermined period after the door is closed, said door also being provided with shutters which are opened automatically when the door is closed, means being provided for automatically closing said shutters, independently of the stack damper, after the door is closed, to admit a gradually decreasing volume of air, to the furnace during a given period after coaling, whereby the combustible gases and floating particles of carbon and tar are consumed, said stack damper being closed during the coaling period, thereby preventing an in rush of cold air to the combustion chamber during the coaling period.

Further, to provide mechanism adapted to be operated by the furnace door, when said door is closing, to open the stack damper of said furnace, said door having shutters for admitting air to said furnace, and mechanism independent of the damper opening mechanism, for opening said shutters when the door is opened, independently operating oil controlled gravity means being connected with said shutter and said damper opening means, wherebysaid damper and said shutters are closed within predetermined periods after the said door is closed.

These objects are accomplished by the c a mechanism illustrated 1n the accompanylng drawings, in which:

Figc 1 18 a front View of a furnace equipped with the improved damper and shutter operating mechanisms. 7

Fig. 2 is a side view of the front portion of the furnace shown in Figure 1.

Figures 8, t and 5 are side views, in different positions, of the cam tappet which actuates the stack damper operating mechanism, and which is operated by the furnace door when the same is being closed.

Fig. 6 is an enlarged horizontal sectional view through the front wall plate of the furnace, on the line 66 of Figure 1,showing the furnace door opened.

Fig. 7 is a vertical sectional view-of the oil controlled gravity valve and its housing, which is used for closing the door shutters and stack damper.

Fig. 8 1s a top view of Figure 7, the cover bemg removed.

Fig.9 is a front view of the air preheater which is secured to the furnace door.

Flg. 10 IS a vertical sectional view enlarged of the door shutters and their supporting frame, and 1 Fig. 11 is a perspective view of the ratclr et member which is actuated by the cam tappet to open the stack damper and lift the gravity valve.

The improved mechanism which is operated to open the said damper by the furnace door when the said door is being closed, contemplates the employment of a smoke abating mechanism, or oxidator, which acts cooperatively with the said damper and which is attached to the furnace door, such oXidator devices being shown and'described in pending applications which were filed by me on the 9th day of October, 1922, for automatically operating oxidators for attachment'to furnace doors for abating smoke, Serial No. 593,475, and for automatically operating shutter opening and closing mechanism for furnace oxidators, Serial No. 593,47 and also for automatically controlled smoke aha-ting oxidators for attachment to furnace doors. filed August 1, 1922, Serial No. 579,050, any one of which may be used in connection with the improved stack damper operating mechanism Referring to the accompanying drawings: The numeral 1 designates the front wall stack damper operating plate of a furnace, 2 the boiler, and 3 the smoke stack which is provided with an ordinary damper 4, which is secured upon a rod 5 which extends transversely through the stack and is pivotally mounted in suitable bearings 6, preferably ball bearings, which are secured to the stack, as clearly shown in Figures 1 and 2. One end of the damper rod .5 extends b'e i 'ond its bearing and has rigidly secured thereon a short level arm 7, to which the upper end of a connecting rod 8 is'pivotally secured, the lower end of which is pivotally secured to lever arm 9, rigidly secured upon a horizontal shaft 10, which is mounted at one end in a bearing 11, which is bolted to the 'front of the furnace, the other end portion of the sait shaft being mounted in the walls of a housing A, which is also bolted to th front of the boiler, and in which is mounted an oil controlled gravity valve,eto be hereinafter described. The shaft 10"is positioned about on a line with the usual'fire door 12 of the furnace, and the housing. A is preferably positioned on the left side of a door which opens toward the "right, as shown in Figure 1. Upon the shaft 10 is loosely mounted the hub-portion 13 of'a cam tappet 13, in position to be engagedby the central portion of the upper edge of the door 152, when the same isclosed, whereby thetappet is swung from a horizontal to a vertical position, or in an arc of a quarter of a circle, and a corresponding partial rotation is thereby iinparted to the shaft 10 in the following manner:

Upon one side of the tappet is pivotally mounted a pawl 14, which engages a tooth of a ratchet segment 15 having 'a hub 16, which is rigidly mounted upon the shaft 10, and the free end of the pawl is provided with alaterally extending pin 17. As the tappetis swung upward by the edge of the door, the ratchet segment, which is en'g ed by the pawl, is thereby turned, together with the shaft 10 and the lever arm 9 as the said shaft lifts the connecting rod 8, by which the lever arm on the damper rod 5 is swung to open the saiddamper. hen the tappet' reaches a nearly vertical position, the pin 17 of the pawl engages the curvedupper edge of a finger 18, which is secured to'the front of the furnace, by whiclrthe pawl is lifted out of engagement with the tooth of the ratchet segmentpthu s leaving the shaft free to be turned in a reverse direction by the mechanism to be presently described, whereby the damper is slowly closed. In order that the tappet may be swung upward through an arc of a quarter of a circle, by the upper edge of the door 12, the doorengaging edge of the tappet, when the tap pet in a horizontal position, incl nes down ward from its free end at an angle of about thirty degrees to the horizontal, for a portion of its length, as shown at 19, in Figures 3, 4 and 5, and then merges into an edge parallel with a horizontal line, as shown at 20, and then terminates in a vertical edge or heel 21. Thus, as the edge of the door er gages and moves against the edge of the tappet, the tappct is swung upward until it assumes a vertical position when the edge of the door passes under the heel 21, as shown by Figure 5, and the tappet is thereby held in a vertical position until the door is again opened, when the tappet is free to swing down to a horizontal position, which position is defined by a stop pin which proects laterally from the bearing block 11 and which is engaged by a lug 23 which projects from the hub portion 13 of the tappet, as clearly shown in Figure 6. As the upper edge of the door moves under the heel 21 of the tappet, the pawl 14; is lifted out of engagement with the tooth of the segment 15, as previously described, thus roleasing the segment and permitting the shaft 10 to be moved in a reverse dir etion, by an oil controlled gravity valve, by which the damper 4 is gradually closed within a predetermined period, said valve being arranged and constructed as follows:

The valve proper isnioun'ted in the metal. housing A, which is secured to the front wall of the furnace by bolts Z, or screws which pass through apertured ears on the .sides of the housing. 'The housing com prises an upper rectangular chamber 2:), from which depends an oil holding cylinder 26, which opens into the chan'iber A hollow piston 27 is mounted in this cylinder, the bottom end wall. of which is provided with a circular axial hole 28, and its upper end is in the form of four radial arms or spokes 29. to which is integrally connected an axial hub 30, in which is inserted the reduced portion of a piston rod 31 in the form of a rack bar having annular teetl '32, thebar being held in the hub by a pin 33 which passes through the hub and thro gh a groove in the said reduced portion of the rack bar, or piston rod, as it will hereinafter be termed.

The piston rod has an axial hole 31", extending through it, the lower portion of whichis threaded, and a stem 3-1 is screwed into the threaded portion ofthe hole and. extends through thehole 28 in the bottom of the piston. The portion of the stern projectinr. through the bottom of the piston is reduced in diameter, as shown at 35, to form a shoulder 36 at the junction of the two diameters, and adisk valve 37. having an afnl il hole, is slipped on the reduced portion and is normally held against theshoulder' 36 by a spiral coilsprii 538, which surrounds the reduced portion of the stem and is held in place by a pin 39 which passes through the reduced portion and engages the lower coil of the spring. The housing is closed by a cap having a threaded hole 41 in line with the axial hole 31 of the piston rod, which is normally closed by a screw 42. The upper end of the stem 34 is formed with a screw driver slot, and by passing a screw driver down through the hole 41 in the cap and into the hole 31 in the piston rod, the valve stem 34 may be adjusted to vary the distance between the diskvalve 37 and the bottom end wall of the piston, by which the period required for the piston to make its downward stroke through the oil in the cy inder maybe lengthened or shortened to meet requirements, for a reason to be hereinafter set forth, and the spring 38 permits the valve to move downward awayfrom the hole 28, under the pressure of the oil when hevalve is raised, so as to permit free passage of the oil through the piston. The portion of the shaft 10 whichpasses through the housing A, has rigidly mounted thereon a segment gear 43, which meshes with the toothed piston rod 31. The rod 8 has connected thereon, midway of its length, a lever arm 44, which is connected by a pivot bolt to a bearing on the front of the furnace. The arm 45 is of the same length as the arms 7 and 9, and therefore they all move in arcs of the same radius, the arm 45 serving only to steady the movement of the rod 8. When the tappet 13 is engaged by the furnace door, as the said door is swung to a closed position, the shaft 10 is thereby given a quarter rotation by the engagement of the pawl 14 with the ratchet segment 15, by which the rod 8 is lifted vertically, thereby opening the damper 4, and simultaneously with the opening of the damper, the segment gear 43 lifts the piston 27 to the'limit of its upward stroke, at which time the pin 17 of the pawl 14 engages the finger 18, and the pawl is thereby lifted out of engagement with the ratchet, thus releasing the shaft 10, which is then turned in a reverse direction by the gravity drop of the piston 27. As the pis ton descends, the rod 8 acts to gradually close the damper 4, the time required for thepiston to drop from its highest to its lowest position being determined by the position of the disk valve 37 with respect to the bottom end of the piston. As the tappet 13 is loosely mounted on the shaft 10, it is held in a vertical positionby the door, which engages the heel 2-1 of the said tappet, and when the door is again opened, the tappet swings by gravity to a horizontal position, and the pawl 14 again engages the tooth of the ratchet segment 15. The pawl is actuated by a spring 14, which also prevents it from swinging back out of operative position.

The damper 4 may be arranged to be fully closed by the down stroke of the piston, as previously described, or if necessary it may be arranged to be nearly, but not entirely,

closed by the said piston, so as always to permit a slight draft through the stack.

The stack damper 4 is adapted to be operated cooperativelywith any one of the improved smoke abating mechanisms previously referred to, and in the accompanying drawings I have shown the furnace door 12 equipped with one of these mechanisms, a description of which is as follows:

The door is provided with a circular opening 1 and upon the outside of the door is bolted a rectangular frame 46, having apertured lugs 47, through which are passed bolts 47 which also pass through the door and through lugs 48 on an air heating device or preheatcr 48, which is thus secured to the inside of the door. The preheater 48, as illustrated in Figures 6 and 9, comprises a flared band, which at its smaller end is slightly greater in diameter than the opening 45 in the door. This band is integrally connected by a series of thin radial plates 49, with a central tubular member 50, which is somewhat longer than the width of the band, and the outer edges of the plates 49 are outwardly curved from the edge of the band to the outer end of the tubular member 50.

Radial plates 51 also extend inwardly from the band and alternate with the plates '49, but the plates 51 terminate before reaching the tubular member 50.

When the furnace door is closed the preheater extends into the combustion chamber of the furnace and therefore becomes heated to a high temperature so that atmospheric air passing through it becomes high- 1y heated before passing over the coal bed of the furnace. i

The frame 46 on the outside of the door is of the same diameter as the hole l -in' the door and is providedwith a series of overlapping shutters 52 in the form of thin metal horizontal blades having apertured lugs on their opposite ends for the reception of pivot pins 54-,which pass through the sides of the frame. The central shutter has a lug 53 on one end only, and upon the opposite end of this shutter is riveted the forked end of a shaft 55, which extends through the adjacent side of the frame 46, and through the sides of a housing 56, which is in all respects a coruiterpart of the hous ing A hereinbefore described. and therefore needs no separate description. The shutters are connected to turn in unison, by a bar 5', which lies between and is pivotally connected to pairs of lugs or ears 5, which are formed on the lower edges of the shutters and centrally of their length.

The shaft 55 carries a segment gear, similar to the gear 43, which meshes with. a

toothed piston rod similar to the rod 31, which carries a valved piston in all respects slmllar to the. piston 2'1 winch Works in an oil housing cylinder 21 forming a part of the said housing. The housing A and its valve, which operates the stack damper, are slightly larger than the housing 56 and its valve, but in other respects are identical as above stated.

The shaft 55 passes through the housing 56, and its outer end carries a tappet 57, which, when the door is opened, is adapted to be engaged by a radial abutment edge 58 on a circular horizontal plate 59 which is adjustably mounted on the hinge pin 60 of the door 12. The back edge of this plate is straight and bears against the front wall of the furnace, as shown in Figure 6, by which the plate is held against a turning movement on the said hinge pin. As the door is swung open, the tappet 57 first engages the edge 58 of the plate by which it is turned from a vertical to a horizontal position and it then passes under the plate by which it is heid in a horizontal position until the door is again closed, when the tappet passes out from under the plate, thus permitting the shutters to begradually' closed by the descent of the oil controlled gravity valve in the housing 56.

The bottoms of the cylinders are slightly concaved and are provided with drain holes 61 which are normally closed by screws 62, by removing which, the oil in the cylinders may be drawn off.

In operation, the cylinders are filled with suitable oil and the valve in each piston is adjusted to control the flow of oil through the piston so that each piston will descend to the limit of its downward stroke within a given period, the valve of the piston which operates the stack damper being adjusted to cause its piston to descend more slowly than the piston which controls the door shutters 52.

Assuming that the pistons are at the limit of their downward strokes, the shutters 52 will be closed, thus preventing air from ontering the furnace through the preheater and the damper 4 will also be closed, thus cutting off the draft through the smoke stack and therefore preventing the escape of heat through the said stack. When it is necessary to stoke the furnace, the fire door is opened and the tappet 57 strikes the straight edge 58 of the plate 59, and is tilted over from a vertical to a horizontal position, and then passes beneath the plate, this movement of the tappet giving the shaft 55 a quarter rotation by which the shutters 52 are swung wide open and the piston in the cylinder 21 is raised to the limit of its upward stroke. As the damper 4: is either entirely closed, or nearly so, as may be determined, when the door is opened for coa-ling, an inrush of cold air to the combustion chamber, during the coaling period, or so long as the door remains open, is prevented.

When the door is closed, it engages the tappet 13 and swings the same from a horizontal to a vertical position, and the damper 4 is opened through the mechanism previously described. Simultaneously with the opening of the said damper, the piston 27 is also lifted to the limit of its upward stroke, but begins to descend the instant the door is fully closed, by the lifting of the pawl 14 from the ratchet segment 15, as previously described.

The closing of the door also permits the tappet 5! to pass from beneath the plate 59, and the shutters 52 begin to close; the time required for the complete closing of the shutters being determined by the adjustment of the disk valve of the piston controlling the said shutters. I

During the closing of the shutters, air in a gradually decreasing volume is admitted to the combustion chamber of the furnace, through the preheater, and is thoroughly mixed with the floating particles of tar and carbon and with the combustible gases,

causing practically complete combustion of these particles, and of the gases, and the consequent elimination of smoke.

As the piston 27, governing the closing of the stack damper A is arranged to close the same more slowly than the shutters 52 are closed, any unconsumed floating products and gases will be carried out'through'the stack with the air which passes through the preheater, and while the damper is wide enough open to induce sufficient draft through the stack for this purpose. But when complete combustion of these particles and gases has been accomplished and nothing in the nature of smoke remains, the damper 4 closes, thus preventing the escape of heated air through the stack. I

Having described my invention, what I claim'as new and desire to secure by Let ters Patent, is:

1. The combination with a furnace having a fire door and a stack provided with a damper; ofa shaft, a tappet loosely mounted thereon, having an inclined edge terrni nating in a heel, and a lever arm, a lever arm on the damper, and a rod connecting said lever arms, a pawl and ratchet connection between said tappet and said shaft, said tappet being engaged by the upper edge of the door when the same is swung to a closed position, and is given a quarter rotation, thereby opening said damper, a preheater on said door, connected shutters on said door for admitting air through said preheater to said furnace, means for automatically opening said shutters when the door is opened, and independent oil controlled gravity pis tons connected respectively with said shutters and said shaft for closing said shutters and said damper within predetermined periods'after the door is closed, said shutter operating piston being raised by the shutter opening mechanism when the door is opened, and said damper operating piston being raised by said shaft when said door is closed.

2. The combination with a furnace having a fire door and a stack provided with a damper; of a shaft on said furnace, lever arms on said damper and said shaft, and a rod connecting said lever arms, a ratchet segment rigidly mounted on said shaft, a tappet loosely mounted on said shaft, a pawl on said tappet adapted to engage said ratchet segment, said tappet being engaged by said door when the same is swung to a closed position, whereby said shaft is turned and said damper opened, means for releasing the pawl from the ratchet as the door closes, and gravity means connected with said shaft to reverse its rotation and close the damper within a predetermined period after the door is closed.

3. The combination with a furnace having a fire door and a stack provided with a damper; of a shaft on said furnace, lever arms on said shaft and said damper and a rod connecting said lever arms, a ratchet segment rigidly mounted on said shaft, a cam tappet loosely mounted on said shaft and having a spring-pressed pawl which engages said ratchet segment, said tappet being engaged by said door when the same is swung to a closed position, whereby said shaft is given a quarter turn by which the damper is opened, a pin projecting from said pawl, and a finger supported in the path of said pin, whereby the pawl is lifted out of engagement with the ratchet as the door closes, a housing on said furnace through which one end portion of said shaft passes, an oil controlled gravity valve in said housing having an adjustable oil valve and a toothed piston rod, a segment gear on said shaft in engagement with said piston rod, whereby said piston is raised simultaneously with the opening of said damper, and gradually. drops by gravity within a predetermined period after the ratchet segment is released by the pawl, said cam tappet being adapted to drop by gravity and its pawl again engages said ratchet segment when the door is opened.

In testimony whereof I aflix my signature.

4 JOHN J. A. MILLER. 

